Background

Pathophysiology

In the past, fibrous papule has been suggested to have been derived from preexisting or involuting melanocytic nevi; however, subsequent investigations appear to have refuted this and have confirmed a relationship to factor XIIIa – positive dermal dendrocytes. Fibrous papule is best considered a variant of angiofibroma.[1]

Sex

Age

History

Physical

The lesions are clinically indistinct. Fibrous papules are usually dome-shaped lesions with a shiny, skin-colored appearance. Occasionally, lesions are sessile, polypoid, or papillomatous. Most of the lesions are firm and indurated. Size usually ranges from 1-5 mm in diameter.

Fibrous papule of the face usually occurs as single lesion, but, occasionally, several lesions may be present.

Most lesions are located on the nose and, less commonly, on the cheeks, chin, neck, and, rarely, on the lip or forehead. Similar papules may be present on the fingers or oral mucosa, where they have been described as reactive nodular hyperplasia or giant cell fibroma.

Causes

Histologic Findings

Fibrous papules are characterized by a proliferation of stellate and spindled cells, a fibrotic stroma, and dilated blood vessels. Occasionally, a sparse inflammatory cell infiltrate of lymphocytes is present.

Acanthosis and an increased number of large polygonal melanocytes may be present in the basal layer. Elastic tissue may be markedly diminished or entirely absent.

View Image

Histopathology of a fibrous papule shows focal fibrosis and vascular proliferation in the upper dermis. Courtesy of Dirk Elston, MD.

Dermal dendritic cells usually stain for factor XIIIa.

Several histological subtypes have been described, which might cause diagnostic difficulties.

Hypercellular fibrous papule is characterized by an increased number of stellate and spindled cells; differential diagnoses include malignant melanoma and atypical fibroxanthoma.[4]

Clear cell fibrous papule shows a proliferation of round clear cells, some with cytoplasm ranging from finely granular to foamy, resembling histiocytes or clear epithelial cells; differential diagnoses include clear cell neoplasm and metastasis.[5] Some authors also differentiate a granular cell fibrous papule, which is similar to the clear cell fibrous papule but seems to contain coarser cytoplasmic granules.[6]

Inflammatory fibrous papule has dense, diffuse dermal infiltrate of predominantly mixed small and large lymphocytes with plasma cells, histiocytes, and rare eosinophils and neutrophils; differential diagnoses include lymphoma, lymphocytic infiltrate, and an infectious process.